Don't punish people who legally pay for what you have to sell by giving them an awkward interface. I haven't seen your app but I can only assume that it won't have the features I like from my favourite pdf viewer (although auto-transpose does sound nice). If I can see it on my screen, I can make as many copies as I like. Not to mention how dof it is that I can only print one copy (photocopier...)
Copy protection does not stop people from pirating, (except for morons) it only annoys paying customers.
just my 2c...
oh, also, 'from abba to zappa' sounds cooler ?